Monoclonal antibody for the detection of advanced glycosylation endproducts in biological samples

ABSTRACT

The present invention relates to monoclonal antibodies to advanced glycosylation endproducts formed in vivo and cross-reactive with advanced glycosylation endproducts formed in vitro, and to methods of diagnosis and therapy based thereon. More particularly, the invention is directed to a monoclonal antibody, or an antigen-binding fragment thereof, reactive with in vivo produced advanced glycosylation endproducts (AGEs), which monoclonal antibody or antigen binding fragment thereof demonstrates an immunological binding characteristic of monoclonal antibody 4G9 as produced by hybridoma 4G9, deposited with the American Type Culture Collection (ATCC) and assigned Accession Number CRL 11626. In a specific embodiment, the 4G9 antibody is used in a sandwich ELISA to detect ApoB-AGE, IgG-AGE, collagen-AGE, serum-AGE peptides and proteins and urinary-AGE peptides and proteins.

FIELD OF THE INVENTION

The present invention relates to monoclonal antibodies to advancedglycosylation endproducts and methods of diagnosis and therapy basedthereon.

BACKGROUND OF THE INVENTION

The present invention relates generally to the detection and measurementof nonenzymatically glycosylated proteins, and particularly to methodsand associated materials for the detection and measurement of proteinsthat have been nonenzymatically glycosylated in vivo.

In the past, notable differences have been observed between thereactivity, chemical identity and immunological characteristics ofadvanced glycosylation endproducts which are produced in vivo andcertain model AGEs which have been characterized over the past severalyears.

Advanced Glycosylation Endproducts (AGEs)

The reaction between glucose and proteins has been known for some time.Its earliest manifestation was in the appearance of brown pigmentsduring the cooking of food. In 1912, Maillard observed that glucose orother reducing sugars react with amino acids to form adducts thatundergo a series of dehydrations and rearrangements to form stable brownpigments (Maillard, 1912, C.R. Acad. Sci. 154:66-68).

In the years that followed the initial discovery by Maillard, foodchemists studied the hypothesized reaction in detail and determined thatstored and heat-treated foods undergo nonenzymatic browning as a resultof the reaction between glucose and polypeptide chains, and that theproteins thereby become crosslinked and exhibit decreasedbio-availability. At this point, it was determined that the pigmentsresponsible for the development of the brown color that develops as aresult of protein glycosylation possessed characteristic spectra andfluorescent properties; however, the chemical structure of the pigmentshad not been specifically elucidated.

The reaction between reducing sugars and food proteins discussed abovewas found in recent years to have its parallel in vivo. Thus, thenonenzymatic reaction between glucose and the free amino groups onproteins to form a stable amino, 1-deoxy ketosyl adduct, known as theAmadori product, has been shown to occur with hemoglobin, wherein arearrangement of the amino terminal of the β-chain of hemoglobin byreaction with glucose forms an adduct and gives a product known ashemoglobin A_(1c). Similar reactions have also been found to occur witha variety of other body proteins, such as lens crystallin, collagen andnerve proteins (see Bunn et al., 1975, Biochem. Biophys. Res. Commun.67:103-109; Koenig et al., 1975, J. Biol. Chem. 252:2992-2997; Monnierand Cerami, in Maillard Reaction in Food and Nutrition, ed. Waller, G.A., American Chemical Society 1983, pp. 431-448; and Monnier and Cerami,1982, Clinics in Endocrinology and Metabolism 11:431-452).

Moreover, brown pigments with spectral and fluorescent propertiessimilar to those of late-stage Maillard products have also been observedin vivo in association with several long-lived proteins, such as lensproteins and collagen from aged individuals. An age-related linearincrease in pigment was observed in human dura collagen between the agesof 20 to 90 years (see Monnier and Cerami, 1981, Science 211:491-493;Monnier and Cerami, 1983, Biochem. Biophys. Acta 760:97-103; and Monnieret al., 1984, "Accelerated Age-Related Browning of Human Collagen inDiabetes Mellitus", Proc. Natl. Acad. Sci. USA 81:583-587).Interestingly, the aging of collagen can be mimicked in vitro in a muchshorter period of time by crosslinking and other non-enzymaticglycosylation (or glycation) reactions induced by incubation of proteinsand other biomolecules (e.g. DNA and phospholipids) in solution withrelatively high concentrations of glucose. The capture of other proteinsand the formation of certain intramolecular adducts on collagen, alsonoted, is theorized to occur by a crosslinking reaction, and is believedto account, for instance, for the observed accumulation of albumin andantibodies in kidney basement membrane (see Brownlee et al., 1983, J.Exp. Med. 158:1739-1744; and Kohn et al., 1984, Diabetes 33:57-59).

Glucose and other reducing sugars attach non-enzymatically to the aminogroups of proteins in a concentration-dependent manner. Over time, theseinitial Amadori adducts can undergo further rearrangements, dehydrationsand cross-linking with other protein groups to accumulate as a family ofcomplex structures referred to as Advanced Glycosylation Endproducts(AGEs). Substantial progress has been made toward the elucidation of thebiological roles and clinical significance of advanced glycosylationendproducts, so that it is now acknowledged that many of the conditionsheretofore attributed to the aging process or to the pathologicaleffects of diseases such as diabetes, are attributable at least in partto the formation, accumulation and/or activity of AGEs in vivo.

As noted above, advanced glycosylation endproducts tend to accumulate onmolecules with long half-lives, especially under conditions ofrelatively high sugar concentration. Thus, AGE accumulation can beindicative of protein half-life, sugar concentration, or both. Thesefactors have important consequences. Numerous studies have suggestedthat AGEs play an important role in the structural and functionalalteration which occurs during aging and in chronic disease.Additionally, advanced glycosylation endproducts are noted to form morerapidly in diabetic and other diseased tissue than in normal tissue.

The "family" of AGEs includes species which can be isolated andcharacterized by chemical structure, some being quite stable, whileothers are unstable or reactive. The reaction between reducing sugarsand the reactive groups of proteins may initiate the advancedglycosylation process. This process typically begins with a reversiblereaction between the reducing sugar and the susceptible group on aprotein for instance, to form a Schiff base, which proceeds to rearrangeto yield the covalently-bonded Amadori rearrangement product. Onceformed, the Amadori product undergoes further non-enzymaticrearrangements and reactions to produce the AGE-modified compound.

Recently, it has been reported that the in vivo oxidation of lipids isin some instances initiated by the reaction of lipids to form lipid-AGEand low density lipoproteins (LDL)-AGE (International Publication No. WO93/13421 by Bucala et al.). More particularly, as the in vivo oxidationof lipids is related to the onset and course of atherosclerosis, themeasurement of lipid-AGE and/or LDL-AGE levels in mammals represents amethod for diagnosing the likelihood or onset of atherosclerosis, ormeasuring the course or severity of the disease, or the efficacy ofanti-AGE treatments. Detection of lipid-AGE or LDL-AGE (in particular,ApoB-AGE) can be used to diagnose or monitor diabetes, as well as formonitoring serum LDL and cholesterol levels.

Antibodies Reactive With AGEs

Efforts have been made to develop antibodies to in vivo-formed AGEs. Forexample, Nakayama et al. (1989, Biochem. Biophys. Res. Commun.162:740-745) studied protein-bound AGEs and in particular, raisedantisera against keyhole limpet hemocyanin (KLH)-AGE in guinea pigs.These antisera exhibited high affinity binding, and the serial dilutioncurves of bovine serum albumin (BSA)-AGE, human serum albumin (HSA)-AGEand ribonuclease (RNase)-AGE were noted to parallel each other,suggesting that a structure in common among these AGE-modified proteinsis recognized by the antisera. Treatment of AGEs with a reducing agentdid not diminish immunoreactivity, suggesting that the antiserumrecognized an AGE, rather than a Schiff base or Amadori product.However, Nakayama et al. do not report the ability of their antisera tobind to in vivo-produced AGEs, or the production of a monoclonalantibody having such properties.

Horiuchi et al.(1991, J. Biol. Chem. 266:7329-32) prepared polyclonaland monoclonal antibodies against bovine serum albumin-BSA. Theseantibodies were reported to recognize AGE-modified proteins formed invitro. Treatment of these AGE-modified proteins with a reducing agenthad no effect on immunoreactivity. In a later publication (Araki et al.,1992, J. Biol. Chem. 267:10211-14), these antibodies were purportedlyanalyzed for purposes of determining reactivity with lens crystallinprotein-AGEs. Makita et al. (1992, J. Biol. Chem. 267:5133-38) reporteddevelopment of a polyclonal rabbit antiserum, which was the firstidentification of development of antibodies reactive with invivo-produced AGEs (see International Publication No. WO 93/13421, whichis incorporated herein by reference in its entirety). In particular,Makita et al. demonstrated the ability of a rabbit RNase-AGE antiserumto bind to tissues from diabetic individuals and to serum componentsknown to contain elevated levels of AGEs. A later publication (Makita etal., 1992, "Hemoglobin-AGE: A Circulating Marker of AdvancedGlycosylation." Science 258:651-653) reported the ability of theseantibodies to detect AGE-modified hemoglobin. The ability to measureAGE-modified hemoglobin is meaningful in detecting the presence ofdiabetes mellitus and the degree of glycemic control in diabeticpatients, which is important for monitoring the long term course of thisdisease, to detect the intensification or worsening of such conditions,or alternatively, the improvement or lessening of the condition, as suchmay occur spontaneously or in conjunction with treatment. Bucala et al.(1993, Proc. Natl. Acad. Sci. USA 90:6434-38) reported that the rabbitanti-RNase-AGE antibodies were also reactive with lipid-AGEs formed invivo. Although the development of polyclonal sera reactive with invivo-formed AGEs finally led to the ability to detect AGEs in biologicalsamples, there remains a need in the art for monoclonal antibodiesreactive with in vivo-produced AGEs.

There is a further need in the art for a monoclonal antibody with higheraffinity binding to AGEs or for specific AGEs than is demonstrated bythe currently available polyclonal antibodies.

The citation of references herein shall not be construed as an admissionthat such is prior art to the present invention.

SUMMARY OF THE INVENTION

The present invention is directed to a monoclonal antibody, or anantigen-binding fragment thereof, reactive with in vivo-producedadvanced glycosylation endproducts (AGEs), particularly where suchmonoclonal antibodies or antigen binding fragments thereof demonstratean immunological binding characteristic of monoclonal antibody 4G9 asproduced by hybridoma 4G9, deposited with the American Type CultureCollection (ATCC) and assigned Accession Number CRL 11626.

More particularly, said monoclonal antibody or antigen-binding fragmentthereof can have an immunological binding characteristic, whichcharacteristic is selected from the group consisting of reactivity withserum-AGE proteins, serum lipid-AGEs, serum-AGE peptides, LDL-AGE andcollagen-AGE.

In a preferred aspect, the monoclonal antibody is humanized or achimeric human-murine antibody. Therapeutic compositions including theantibody or active fragments thereof, or agonists and cognate molecules,or alternately, antagonists of the same, and methods of use of suchcompositions in the prevention, diagnosis or treatment of disease usingthese compositions are also included, wherein an effective amount of thecomposition is administered to a patient in need of such treatment.

The antigen-binding fragment of the monoclonal antibody can be a singlechain Fv fragment, an F(ab') fragment, an F(ab) fragment, and an F(ab')₂fragment, or any other antigen-binding fragment.

In a specific embodiment, infra, the monoclonal antibody or fragmentthereof is a murine IgG isotype antibody; more particularly, themonoclonal antibody or fragment thereof can be monoclonal antibody 4G9as produced by hybridoma 4G9, deposited with the American Type CultureCollection (ATCC) and assigned Accession Number CRL 11626.

Naturally, the invention extends to a hybridoma that produces monoclonalantibody 4G9, which hybridoma is deposited with the ATCC and assignedAccession Number CRL 11626.

The monoclonal antibody of the invention advantageously binds to invivo-produced AGEs. Accordingly, in another aspect, the invention isdirected to a method for detecting the presence of advancedglycosylation endproducts (AGEs) in a biological sample. The methodcomprises contacting a sample suspected of containing AGEs with themonoclonal antibody or antigen binding fragment thereof of the inventionunder conditions which allow for the formation of reaction complexescomprising the monoclonal antibody or antigen binding fragment thereofand the AGEs; and detecting the formation of such reaction complexescomprising the monoclonal antibody or antigen binding fragment thereofand AGEs in the sample. Detection of the formation of reaction complexesindicates the presence of AGEs in the sample.

In one embodiment, sample molecules may be allowed to bind or adhere toa solid support and the AGE-modified molecules so immobilized may berecognized by formation of reaction complexes with the monoclonalantibody of the present invention or an antigen-binding fragmentthereof, through subsequent assay steps to detect reaction complexes.

In a further embodiment, the monoclonal antibody or antigen-bindingfragment thereof is bound to a solid phase support, for instance as thefirst component of a "sandwich-type" assay for AGE-modified moleculesreactive with the immobilized monoclonal antibody of the presentinvention, or an antigen-binding fragment thereof, wherein the secondimmunological binding partner may be a polyclonal or a monoclonalantibody, or a mixture thereof, including without limitation themonoclonal antibody of the present invention. In a further embodiment,the sample is contacted with a labelled advanced glycosylationendproduct (AGE), and unbound substances are removed prior to detectingthe formation of reaction complexes in a competitive assay format.Formation of reaction complexes with the sample is detected by observinga decrease in the amount of labelled AGE bound in the assay.Alternatively, the formation of reaction complexes can be observed bydetecting the binding of a labelled anti-AGE antibody or an antibody toan AGE carrier, such as but not limited to albumin, hemoglobin, lowdensity lipoprotein, and the like, to the complex of the monoclonalantibody or antigen-binding fragment thereof and the AGE.

In another embodiment, an AGE is bound to a solid phase support. In afurther aspect, the sample is contacted with said immobilized AGE boundto the solid phase support, in the presence of the monoclonal antibodyof the present invention or an antigen-binding fragment thereof. Themonoclonal antibody or antigen-binding fragment thereof is labelledeither directly or by further assay steps using available reagents thatspecifically recognize the monoclonal antibody of the present inventionor an antigen-binding fragment thereof. Formation of reaction complexeswith AGE-modified molecules in the sample is detected by observing adecrease in the amount of label complexed to the solid phase support.

The methods for detecting the presence of AGEs in a sample according tothe invention are useful for evaluating the level of AGEs in abiological sample. Accordingly, the invention is further directed to amethod for evaluating the level of AGEs in a biological sample, whichcomprises detecting the formation of reaction complexes in a biologicalsample; and evaluating the amount of reaction complexes formed, whichamount of reaction complexes corresponds to the level of AGEs in thebiological sample.

The level of AGEs in a sample can have a strong diagnostic or prognosticvalue. Accordingly, the invention is further directed to a method fordetecting or diagnosing the presence of a disease associated withelevated AGE levels in a mammalian subject comprising evaluating thelevel of AGEs in a biological sample from a mammalian subject; andcomparing the level detected to a level of AGEs normally present in themammalian subject. An increase in the level of AGEs as compared tonormal levels indicates a disease associated with elevated levels ofAGEs. Similarly, the invention relates to a method for monitoring thecourse of a disease associated with elevated AGE levels in a mammaliansubject comprising evaluating the level of AGEs in a series ofbiological samples obtained at different times from a mammalian subject.An increase in the level of AGEs over time indicates progression of thedisease, and a decrease in the level of AGEs over time indicatesregression of the disease. Also, the invention relates to a method formonitoring a therapeutic treatment of a disease associated with elevatedAGE levels in a mammalian subject comprising evaluating the levels ofAGEs in a series of biological samples obtained at different times froma mammalian subject undergoing a therapeutic treatment for a diseaseassociated with elevated AGE levels. A decrease in the level of AGEsover time indicates an effective therapeutic outcome.

The invention advantageously provides convenient test kit formats forpracticing the foregoing methods. Accordingly, the invention provides atest kit for measuring the presence or amount of in vivo-derived AGEs inan analyte. Such a kit can comprise a monoclonal antibody of theinvention or an antigen-binding fragment thereof of the invention; meansfor detecting the formation of reaction complexes between the monoclonalantibody or antigen-binding fragment thereof and AGEs; other reagents;and directions for use of the kit. In one embodiment, the test kit canfurther comprise preparation of an AGE or AGEs, or molecules modified byan AGE or AGEs, recognized by the monoclonal antibody, e.g., whereinsaid AGE molecules are irreversibly associated with a solid phase. Inanother embodiment, the test kit can further comprise a labelledanti-AGE antibody or antigen-binding fragment thereof, which labelledanti-AGE antibody is reactive with in vivo-produced AGEs, or directlyreactive with the analyte molecule whose degree of AGE-modification isto be determined, including for instance a labelled anti-low densitylipoprotein antibody.

Thus, a primary object of the invention is to provide a monoclonalantibody reactive with in vivo-produced AGEs.

A further object of the invention is to provide an indefinite source ofan antibody reactive with in vivo-produced AGEs, which antibody hasparticular immunological binding characteristics that render itparticularly useful for this purpose.

Yet a further object of the invention is to provide an assay fordetecting low density lipoprotein-AGE, particularly ApoB-AGE.

A still further object of the invention is to provide therapeuticcompositions and corresponding methods for treating conditionscharacterized by abnormal levels of AGEs which are based on or includethe antibodies of the present invention.

These and other objects of the invention will be better understood byreference to the following drawings, detailed description of theinvention, and the Examples.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph demonstrating the recognition of LDL-AGE by means ofthe present invention.

FIG. 2 depicts a graph showing the detection of IgG-AGE complexes inserum by means of the present invention.

FIG. 3 is a graph depicting the detection and measurement of serumpeptide-AGE levels in normals and diabetics by means of the presentinvention.

FIG. 4 is a graph depicting the results of the detection and measurementof urinary AGE levels by means of the present invention.

FIG. 5 is a graph depicting the results of the measurement ofcollagen-AGE levels in rat skin by means of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a monoclonal antibody, or anantigen-binding fragment thereof, reactive with in vivo-producedadvanced glycosylation endproducts (AGEs). In particular, saidmonoclonal antibody or antigen binding fragment thereof can demonstratethe immunological binding characteristics of monoclonal antibody 4G9 asproduced by hybridoma 4G9, deposited with the American Type CultureCollection (ATCC) and assigned Accession Number CRL 11626. Naturally,the invention extends to the hybridoma as well. Thus, the inventionadvantageously provides an indefinitely prolonged cell source of amonoclonal antibody of the invention: the hybridoma.

The invention further relates to diagnostic assay methods and kits thatcomprise the monoclonal antibody of the invention and to therapeuticmethods based thereon.

Various terms are used herein, which have the following meanings:

A molecule is "antigenic" when it is capable of specifically interactingwith an antigen recognition molecule of the immune system, such as animmunoglobulin (antibody) or T cell antigen receptor. An antigenicpolypeptide contains at least about 5, and preferably at least about 10,amino acids. An antigenic portion of a molecule can be that portion thatis immunodominant for antibody or T cell receptor recognition, or it canbe a portion used to generate an antibody to the molecule by conjugatingthe antigenic portion to a carrier molecule for immunization. A moleculethat is antigenic need not be itself immunogenic, i.e., capable ofeliciting an immune response without a carrier.

Where present, the term "immunological binding characteristics," orother binding characteristics of an antibody with an antigen, in all ofits grammatical forms, refers to the specificity, affinity,cross-reactivity, and other binding characteristics of an antibody.

The term "adjuvant" refers to a compound or mixture that enhances theimmune response to an antigen. An adjuvant can serve as a tissue depotthat slowly releases the antigen and also as a lymphoid system activatorthat non-specifically enhances the immune response (Hood et al.,Immunology, Second Ed., 1984, Benjamin/Cummings: Menlo Park, Calif., p.384). Often, a primary challenge with an antigen alone, in the absenceof an adjuvant, will fail to elicit a humoral or cellular immuneresponse. Adjuvants include, but are not limited to, complete Freund'sadjuvant, incomplete Freund's adjuvant, saponin, mineral gels such asaluminum hydroxide, surface active substances such as lysolecithin,pluronic polyols, polyanions, peptides, oil or hydrocarbon emulsions,keyhole limpet hemocyanins, and potentially useful human adjuvants suchas BCG (bacille Calmette-Guerin) and Corynebacterium parvum. Preferably,the adjuvant is pharmaceutically acceptable.

The present invention advantageously provides methods for preparingmonoclonal antibodies having the binding characteristics of monoclonalantibody 4G9 by immunizing with an antigen such as Rnase-AGE,lysozyme-AGE, BSA-AGE and KLH-AGE. Any such antigen may be used as animmunogen to generate antibodies with the immunological characteristicsof monoclonal antibody 4G9. Such antibodies include but are not limitedto monoclonal, chimeric, single chain, Fab fragments, and an Fabexpression library.

Various procedures known in the art may be used for the production ofpolyclonal antibodies corresponding to the monoclonal antibody of thepresent invention. For example, reproduction of antibody may proceed bythe immunization of various host animals. In this embodiment, theantigen may be conjugated to an immunogenic carrier, e.g., bovine serumalbumin (BSA) or keyhole limpet hemocyanin (KLH), or the carrier may bereacted with a reducing sugar such as glucose such that the carrierbears AGE determinants. Various adjuvants such as those set forth above,may be used to increase the immunological response, depending on thehost species.

For production of monoclonal antibodies of the present invention, anytechnique that provides for the production of antibody molecules bycontinuous cell lines in culture may be used. These include but are notlimited to the hybridoma technique originally developed by Kohler andMilstein (1975, Nature 256:495-497), as well as the trioma technique,the human B-cell hybridoma technique (Kozbor et al., 1983, ImmunologyToday 4:72), and the EBV-hybridoma technique to produce human monoclonalantibodies (Cole et al., 1985, in Monoclonal Antibodies and CancerTherapy, Alan R. Liss, Inc., pp. 77-96). In an additional embodiment ofthe invention, monoclonal antibodies can be produced in germ-freeanimals utilizing recent technology (PCT/US90/02545). According to theinvention, human antibodies may be used and can be obtained by usinghuman hybridomas (Cote et al., 1983, Proc. Natl. Acad. Sci. U.S.A.80:2026-2030) or by transforming human B cells with EBV virus in vitro(Cole et al., 1985, in Monoclonal Antibodies and Cancer Therapy, Alan R.Liss, pp. 77-96). In fact, according to the invention, techniquesdeveloped for the production of "chimeric antibodies" or "humanizedantibodies" (Morrison et al., 1984, J. Bacteriol. 159-870; Neuberger etal., 1984, Nature 312:604-608; Takeda et al., 1985, Nature 314:452-454)by splicing the genes from a mouse antibody molecule of the presentinvention, e.g., monoclonal antibody 4G9, together with genes from ahuman antibody molecule of appropriate biological activity can be used;such antibodies are within the scope of this invention. Chimericantibodies are those that contain a human Fc portion and a murine (orother non-human) Fv portion; humanized antibodies are those in which themurine (or other non-human) complementarity determining regions (CDR)are incorporated in a human antibody; both chimeric and humanizedantibodies are monoclonal. Such human or humanized chimeric antibodiesare preferred for use in in vivo diagnosis or therapy of human diseasesor disorders (described infra), since the human or humanized antibodiesare much less likely than xenogeneic antibodies to induce an immuneresponse, in particular an allergic response.

According to the invention, techniques described for the production ofsingle chain antibodies (U.S. Pat. No. 4,946,778) can be adapted toprovide single chain antibodies of the present invention. An additionalembodiment of the invention utilizes the techniques described for theconstruction of Fab expression libraries (Huse et al., 1989, Science246:1275-1281) to allow rapid and easy identification of monoclonal Fabfragments with the desired specificity for the antibody of the presentinvention, or its derivatives, or analogs.

Antibody fragments which contain the idiotype of the antibody moleculecan be generated by known techniques. For example, such fragmentsinclude but are not limited to: the F(ab')₂ fragment which can beproduced by pepsin digestion of the antibody molecule; the Fab'fragments which can be generated by reducing the disulfide bridges ofthe F(ab')₂ fragment, and the Fab fragments which can be generated bytreating the antibody molecule with papain and a reducing agent. Suchantibody fragments can be generated from any of the polyclonal ormonoclonal antibodies of the invention; preferably, such antibodyfragments are generated using monoclonal antibody 4G9.

In the production of antibodies, screening for the desired antibody canbe accomplished by techniques known in the art, e.g., radioimmunoassay,ELISA (enzyme-linked immunosorbent assay), "sandwich" immunoassays,immunoradiometric assays, gel diffusion precipitin reactions,immunodiffusion assays, in situ immunoassays (using colloidal gold,enzyme or radioisotope labels, for example), western blots,precipitation reactions, agglutination assays (e.g., gel agglutinationassays, hemagglutination assays), complement fixation assays,immunofluorescence assays, protein A assays, and immunoelectrophoresisassays, etc. In one embodiment, antibody binding is detected bydetecting a label on the primary antibody. In another embodiment, theprimary antibody is detected by detecting binding of a secondaryantibody or other reagent to the primary antibody. In a furtherembodiment, the secondary antibody is labeled. Many means are known inthe art for detecting binding in an immunoassay and are within the scopeof the present invention. For example, to select antibodies inaccordance with the present invention, one may assay generatedhybridomas for a product which binds to in vivo-formed or invitro-formed AGEs. Alternatively, such an antibody can be selected onthe basis of an ability to compete for binding of monoclonal antibody4G9 to such AGEs.

The foregoing antibodies can be used in methods known in the artrelating to the localization and activity of AGE-modified proteins ortissues, e.g., for Western blotting, ELISA, detecting AGE-modifiedtissue in situ, measuring levels of AGE-modified molecules, for instanceincluding proteins, peptides, lipids and nucleic acids, and, inparticular, hemoglobin-AGE, immunoglobulin-AGE, and LDL-AGE, inappropriate physiological samples, such as serum samples.

Using the present invention, one can assess and/or detect the presenceof stimulated, spontaneous, or idiopathic pathological states inmammals, by measuring the corresponding presence of advancedglycosylation endproducts. More particularly, the presence or amount ofthe AGEs may be followed directly by assay techniques such as thosediscussed herein, for example through the use of an appropriatelylabeled quantity of the present anti-AGE monoclonal antibody, as setforth herein.

The tissue and end organ damage caused by advanced glycosylationaccumulates over a period of months to years. Diabetic complicationsprogress over a similar duration, so that it is advantageous to detectearlier the AGE accumulation that has been linked to the development ofpathology in such disease states.

In particular, the monoclonal antibody of the invention can be used todetect the presence of AGEs such as but not limited to, hemoglobin-AGE,albumin-AGE, lipid-AGEs, and AGE-modified peptides. Generally, thepresence of a disease or disorder associated with AGEs can be assessedby detecting higher levels of AGEs in a biological sample from a subjectwho suffers from such a disease or disorder, as compared to a normalindividual. The effectiveness of an agent, e.g., aminoguanidine, toprevent or inhibit the formation of AGEs can be evaluated by observing adecrease in the level of AGEs in biological samples obtained from asubject over a time interval.

For example, Hb-AGE has been determined to account for about 0.42% ofcirculating human hemoglobin. This fraction increases to approximately0.75% in patients with diabetes-induced hyperglycemia. Of significance,diabetic patients treated for 28 days with aminoguanidine, an inhibitorof AGE formation in vivo, show significantly decreased levels of Hb-AGEat the end of the treatment period (International Publication No. WO93/13421).

The present invention also extends to the measurement of other AGEs andparticularly serum and urinary AGE-modified proteins and AGE-modifiedpeptides. Serum and urinary AGE-modified peptides, like lipid-AGE andHb-AGE, represent circulating markers of AGE accumulation that reflectthe onset and extent of pathologies and other dysfunctions where suchaccumulation is a characteristic. Thus, those AGE-related and diabeticconditions where increased levels of AGEs have been observed, such as,for example, atherosclerosis, cataracts and diabetic nephropathy, may bemonitored and assessed over the long term by the measurement of theseAGEs, particularly by resort to the diagnostic methods disclosed herein.

Similarly, serum peptide-AGEs can be used as an indicator that reflectsglomerular filtration rate (GFR) and kidney damage. Urinary peptide-AGEsmay be used as an indicator to measure the turnover in tissue proteins,and more particularly, tissue protein bearing AGE modifications.

In the LDL-AGE, Hb-AGE, and the serum peptide-AGE assays, a blood sampleis drawn and a separation procedure can be used. For measuring the levelof LDL- or lipid-AGEs, a procedure such as that described inInternational Publication No. WO 93113421 by Bucala et al. can be used.For detecting hemoglobin-AGE, the cellular blood components can beseparated from the serum, and hemoglobin can be extracted from the redblood cells. The serum level of LDL-AGE, peptide-AGEs and the presenceor extent of Hb-AGEs present can then be evaluated.

By conducting these tests with a single blood sample, a broader timeframe at which blood glucose levels become uncontrolled can beestimated, e.g., a 60 day range predictable by Hb-AGE for instance,extends the period to be assessed for glycemic control to before the 3-4week time frame which is measured by Hb-A_(1c) determination. Ifdesired, the analyses of Hb-AGE and serum peptide-AGEs can be runtogether with a glucose level determination in blood or urine, a glucosetolerance test, and other tests useful for assessing diabetes controlincluding the measurement of urinary peptide-AGEs, to give a completepatient profile.

In a preferred aspect of the invention, LDL-AGEs are measured using themonoclonal antibody of the invention in combination with either ananti-LDL (such as, but not limited to, anti-ApoB) antibody or apolyclonal anti-AGE antibody (such as rabbit anti-RNase-AGE).

Another aspect of the invention addresses advanced glycosylationendproducts which can be detected in the urine. Proteins, includingpeptides, are excreted in the urine in very low amounts in normalindividuals, and at elevated levels in diseased individuals. Thepresence and/or level of urinary peptide-AGEs reflective of the turnoverof tissue AGEs can be determined, correlated to and predictive ofparticular diseases or conditions.

The presence of peptides in the urine may be a symptom of numerousdiseases or conditions reflective of a net catabolic state as wouldexist when the host or patient is undergoing invasion as by infection.Under such circumstances, the host mobilizes against the invasivestimulus by the secretion of numerous factors such as cytokines thatsuspend the anabolic energy storage activity and cellular repairactivities and promote instead the catabolic depletion of energy storesand the recruitment of leukocytes and other factors to fight andneutralize the stimulus. The measurement of urinary peptide-AGEsprovides yet another index of possible invasive activity in the host,such as cachexia and shock. Thus, one can measure the presence or levelof peptide-AGEs in urine, and correlate this level to a standard. Innormal individuals, the normal level may be low. In diabetic patients,the level of peptide-AGEs may be greater. Alternatively, in a subjectsuffering from AGE-associated advanced renal disease, the level ofurinary peptides may be greatly decreased owing to the onset of renalfailure. In patients experiencing infection or other trauma, the levelof peptide-AGEs may be significantly greater than in normal individuals.Thus, the advancement or worsening of diabetes prior to the onset ofrenal complications, the onset of renal complications associated withdiabetes or other AGE-related diseases, or the presence of infectioncould be detected by detecting urine levels of peptide-AGEs.

The anti-AGE monoclonal antibody of the invention can also be used inthe treatment of patients to reduce the level or accelerate the removalof circulating AGEs or AGE-modified molecules, or similar such AGEs orAGE-modified molecules, which may be present in abnormally elevatedlevels in certain tissues, e.g., pancreas, liver, kidney or brain, andwhich AGEs may be undesired.

Additionally, it is within the scope of the invention described hereinto utilize the anti-AGE monoclonal antibody for the design, screeningand/or potentiation of drugs or compounds which are useful for treatingelevated levels of AGEs in vivo. In this connection, the anti-AGEmonoclonal antibody may be used to purify proteins that have beenspecially cultivated or, produced for use as therapeutic agents. Thetherapeutic use of such proteins is increasing in prominence andimportance, and such exogenous proteins (like the host's own tissue andcirculating proteins) are susceptible to glycation and the formation ofAGEs. Such AGEs are chemically reactive and biologically active, so itis desirable to limit their introduction into a host during therapy. Asa consequence, the present invention includes a method for purificationof batches of such proteins by bringing them into contact with, forexample, a quantity of the anti-AGE monoclonal antibody of the presentinvention or an antigen-binding fragment thereof, immobilized on asuitable substrate. In this way the glycosylated proteins could beseparated from the rest of the batch by conventional procedures. Thesubstrate could be refreshed or replaced periodically in the instance ofa commercial process, so that a continuous circulation of proteinmaterial past the substrate and subsequent separation of the protein-AGEcomponent could be conducted. Naturally, the foregoing scheme ispresented for purposes of illustration only, and is capable of variousmodifications in design and execution within the skill of the art andthe scope of the invention.

All of the protocols disclosed herein may be applied to the qualitativeand quantitative determination of advanced glycosylation endproducts andto the concomitant diagnosis and surveillance of pathologies in whichthe accretion of advanced glycosylation endproducts is implicated. Suchconditions as diabetes and the conditions associated with aging, such asatherosclerosis and skin wrinkling represent non-limiting examples, andaccordingly methods for diagnosing and monitoring these conditions areincluded within the scope of the present invention.

The present invention also includes assay and test kits for thequalitative and/or quantitative analysis of the extent of the presenceof advanced glycosylation endproducts. Such assay systems and test kitsmay comprise a labeled component prepared, e.g., by one of theradioactive and/or enzymatic techniques discussed herein, coupling alabel to the anti-AGE monoclonal antibody of the present invention or anantigen-binding fragment thereof, or to a binding partner thereof. Oneof the components of the kits described herein is the anti-AGEmonoclonal antibody of the present invention or the antigen-bindingfragment thereof, in labeled or non-labeled form.

As stated earlier, the kits may be used to measure the presence ofadvanced glycosylation endproducts on recombinant or other purifiedproteins, and particularly those destined for therapeutic use, to assaythem for AGE presence in a first instance, and in a second instance, toassist in their further purification free from material with undesiredAGE modifications.

In accordance with the testing techniques discussed above, one class ofsuch kits will contain at least the monoclonal antibody or anantigen-binding fragment thereof of the invention, means for detectingimmunospecific binding of said antibody or fragment thereof to AGEcomponents in a biological sample, and directions, of course, dependingupon the method selected, e.g., "competitive", "sandwich", "DASP" andthe like. The kits may also contain peripheral reagents such as buffers,stabilizers, etc.

More specifically, the preferred diagnostic test kit may furthercomprise a known amount of a binding partner to an anti-AGE antibody asdescribed above, generally bound to a solid phase to form animmunosorbent, or in the alternative, bound to a suitable label.

A test kit of the invention may also further comprise a second antibody,which may be labelled or may be provided for attachment to a solidsupport (or attached to a solid support). Such an antibody may be, forexample, an anti-AGE antibody, or an antibody specific for the non-AGEportion of the analyte to be assessed for AGE modification, or anAGE-component. Examples of the latter include, but are not limited to,anti-hemoglobin, anti-albumin, and, as shown herein, anti-ApoB. Suchantibodies to the "carrier" portion of an AGE component can bepolyclonal or monoclonal antibodies.

The present invention will be better understood by reference to thefollowing Examples, which are illustrative of the invention, and are notintended as limiting of the invention. Where present, the designation"PBS" denotes phosphate-buffered saline. PBS may be prepared bydissolving 8.0 grams of NaCl, 0.2 grams of KCl, 1.44 grams of Na₂ HPO₄,and 0.24 grams of KH₂ PO₄ in 800 ml of distilled water, adjusting the pHto 7.2, and the volume to 1 liter. The resulting solution may bedispensed in convenient volumes and sterilized by autoclaving, and maybe stored at room temperature. Likewise, the terms "Wash Solution" and"TBS-T Wash Solution" where present refer to the following: TrisBuffered Saline-Tween (TBS-T) (0.01M Trizma, 0.15M NaCl, 0.05% Tween-20,0.02% sodium azide, adjusted to pH 7.4 with HCl). The term "AssayBuffer" refers to a solution generally containing 25 mM-1 M borate, pH8.0, 150 mM NaCl, 0.01% EDTA and 1% BSA. The concentrations of thecomponents comprising the Assay Buffer as may appear in the Exampleslisted below may vary within the scope of the present invention.Naturally the foregoing formulations are illustrative and may varywithin the skill of the art, and are presented herein in fulfillment ofthe duty to present the best mode for the practice of the invention.

EXAMPLE 1 A HYBRIDOMA THAT SECRETES AN AGE--SPECIFIC MONOCLONAL ANTIBODY

The present Example describes production of a monoclonal antibody thatreacts with in vivo-produced AGEs.

Preparation of Immunogen

One gm of KLH (Sigma Cat.#2133) was combined with 96 gm glucose in 500ml of a 400 mM sodium phosphate buffer, pH 7.4. The solution wasdeoxygenated by bubbling nitrogen into the solution, and filtersterilized by passing the solution through a 0.2 micron celluloseacetate filter. After incubation at 37° C. for 90 days, the solution wasdialyzed against a 20 mM sodium phosphate buffer, containing 0.15 MNaCl, pH 7.4. The protein content was determined using a Lowry assay,again filter sterilized, and aliquoted. The aliquots were stored at -80°C. until used.

Immunization Schedule

Five mice were pre-bled and earmarked. Each mouse was immunizedsubcutaneously with 0.2 ml of a preparation containing 100 μg of AGEmodified-KLH in PBS (Immunogen) mixed 1:1 with Complete Freund'sAdjuvant (CFA). Mice were boosted subcutaneously at day 21 with 0.2 mlof 50 μg of Immunogen in Incomplete Freund's Adjuvant (IFA). A secondboost of 50 μg of Immunogen in IFA was administered on day 41 as before.Finally, a third boost of 50 μg of Immunogen in IFA was administered onday 63 as before and a test bleed taken from the tall vein and serumprepared. The mouse showing the highest titer as determined in theAntisera Test Bleed Titering procedure described below was selected andboosted intravenously with 0.1 ml containing 50 μg of Immunogen withoutadjuvant. Three days later, the spleen was removed and the animalexsanguinated.

Antisera Test Bleed Titering

An initial dilution of 1/100 of each serum sample to be titered wasprepared in PBS containing 0.1% BSA, followed by 10 serial 2-folddilutions in the same buffer for titer determination. Pre-immune seranoted above were diluted in the same manner as the immune sera and usedas controls. Microtiter wells were coated with 1.5 μg of BSA-AGE antigenprepared by incubating bovine serum albumin (BSA) from Calbiochem,Catalog #12657, as described by Makita et al., J. Biol. Chem., 267(8),pp. 5133-5138 (1992). The antigen coated wells were sealed with Mylarsealing tape (Corning) and incubated overnight at 4° C. The microtiterplates were subsequently washed 6 times with TBS-T Wash Solution andblocked for one hour at 37° C. by adding 200 ul of a solution of PBScontaining 0.2% BSA and 0.2% sodium azide. The microtiter plates werewashed as before and 100 ul of the dilutions of pre-immune and immunesera were added. After incubation for 2 hrs. at room temperature, themicrotiter plates were washed as described above and 100 ul of a goatanti-mouse IgG (gamma chain specific) horseradish peroxidase-conjugatedantibody (Sigma) was added to all wells and incubated for 1 hr. at 37°C. The microtiter plates were washed as before and 100 ul of OPDPeroxidase Substrate (Sigma) was added to all wells and incubated for 30minutes at room temperature. After the incubation period, the plateswere read at 450 nm on a microtiter plate reader.

Hybridoma production was carried out by fusing the mouse spleen cellswith the myeloma X63AG8.653 cell line as described elsewhere (Harlow, E.and D. Lane, Antibodies: A Laboratory Manual, Cold Spring HarborLaboratory, 1988).

Hybridoma Screening Procedure

After fusion of spleen cells with the myeloma cell line, 1 drop of the50 ml fusion mixture was added to each of 96 wells in 10 microwell cellculture plates (Corning). The plates were numbered 1 to 10, the rows ofeach plate by letter, and the columns by number to give a coding systemthat identified the parental cell cultures that developed from each dropof the fusion mixture. After culture in selection media described inHarlow and Lane, supra., hybridoma cultures were screened for antibodyproduction to AGE antigen as follows:

BSA-AGE coated wells were prepared as described in the Antisera TestBleed Titering section above. Further, BSA was coated on wells followingthe same coating procedure as with BSA-AGE to detect any nonspecificbinding. The antigen coated plates were used to screen cell culturesupernates from each of the parental cultures. The parental supernateswere diluted 1:2 in PBS containing 0.2% BSA and 100 μl of each added toone well of a BSA-AGE coated microtiter plate and to one well of a BSAcoated plate. The plates were incubated at room temperature for 2 hoursand subsequently washed 6 times with TBS-T Wash Solution. One hundred μlof a goat anti-mouse IgG (gamma chain specific) horseradishperoxidase-conjugated antibody diluted 1:1000 in PBS containing 1% BSAwas added to each well and the procedure followed as in the AntiseraTest Bleed Titering section above. Sixteen parental cultures were foundto produce absorbance readings exceeding 0.3 O.D. on the BSA-AGE wellsand no reactivity on the BSA coated wells. The latter parental cultureswere expanded in culture in 24 well macrowell plates (Corning) and uponfurther supernatant/antibody evaluation, three parental cultures werere-cloned (secondary cloning). Following a procedure described in Harlowand Lane, supra., the parental cultures were diluted in RPMI 1640culture medium containing 20% fetal bovine serum to give a cell densityof 0.5-10 cells per well on wells that were precultured with splenocytefeeder cells.

After two weeks only one parental cell culture, designated 5D2, yielded17 AGE-specific producing antibody clones identified by testing theculture supernates in the screening procedure above. The other twoparentals did not yield any positive subclones. After expansion of the17 clones of 5D2 in cell culture, one clonal culture was selected thathad high viability and produced the highest titer antibody to BSA-AGE inthe aforementioned antibody screening assay. A further subcloning of thelatter was done to assure monoclonality and the resultant clonedesignated 4D6 (5D2-4D6). A tertiary cloning of 5D2-4D6 was done asabove, and 10 subclones were identified that produced good titers toBSA-AGE from the 0.3 cells/well dilution. One was selected from thisgroup designated 4G9 (5D2-4D6-4G9) based on a comparative affinityanalysis in accordance with Macdonald et al. (Macdonald, R. A. et al.1988. Journal of Immunological Methods, 106:191-194). The cells fromeach culture were prepared in accordance with Harlow and Lane, supra.for frozen storage. 4G9 was expanded in culture and adapted to aprotein-free medium (MaxiCell/Hybridoma-PF Medium, Cat. No. N10105,Atlanta Biologicals, Norcross, Ga.) for monoclonal antibody production.

EXAMPLE 2 BINDING AND IMMUNOLOGICAL CHARACTERISTICS OF THE AGE-SPECIFICMONOCLONAL ANTIBODY 4G9

The ability of monoclonal antibody, mAb 4G9, raised against KLHnon-enzymatically glycated by prolonged incubation with glucose(KLH-AGE) to recognize a variety of the non-enzymatically glycatedproteins and peptides produced by browning with various sugars wasdetermined.

Materials and Methods

Production of AGE proteins. All proteins and peptides were browned withglucose, ribose or glucose 6-phosphate in 300 mM sodium phosphatebuffer, pH 7.4, for 8-12 weeks at 37° C. The control proteins weretreated the same way except the sugars were omitted. Direct ELISA andcompetition ELISA. For direct ELISA, BSA-AGE or modified BSA was coatedon microtiter plates, the unbound sites were blocked by incubation withAssay Buffer (25 mM borate, pH 8.0, 150 mM NaCl, 0.01% EDTA and 1% BSA).The plate was washed 6X and increasing concentrations of mAb in AssayBuffer were added. After this incubation, the plate was again washed andincubated with alkaline-phosphatase labeled goat anti-mouse antibodies(Cappel, Durham, N.C.) diluted 1:1000 in Assay Buffer. The unboundantibodies were removed by extensive washing and the bound antibodieswere detected by addition of p-nitrophenylphosphate in recording theoptical density at 410 nm.

The competition ELISA was performed by pre-coating microtiter plateswith BSA-AGE and blocking with Assay Buffer. The plate was washed andmAb 4G9 and increasing concentrations of the competitors listed in Table1 were added and simultaneously incubated for 1 hr at 37° C. The unboundmaterials were removed by extensive washing and the bound mAb wasdetected with alkaline phosphatase labeled anti-mouse antibodies similarto direct ELISA. All washes were in TBS-T wash solution; all incubationsproceeded for 1 hr at 37° C.

Results

Interaction of mAb 4G9 with various browned compounds. Monoclonalantibody 4G9 (described in Example 1, above) displayed a broad range ofrecognition of proteins and peptides which were browned, i.e. incubatedto acquire AGE modification, with different sugars. Table 1 shows aseries of examples of the browned compounds which bound with this mAb inthe competition assay indicating that AGE structures are importantantigenic determinants for this antibody. The mAb showed no significantbinding to any unglycated protein nor to any sugars assayed in the samemanner as the glycated species.

                  TABLE 1                                                         ______________________________________                                        protein or peptide                                                                           sugar          IC.sub.50 M                                     ______________________________________                                        BSA            glucose        3 × 10.sup.-9                             Rat serum albumin                                                                            glucose-6-phosphate                                                                          5 × 10.sup.-9                             Hemoglobin     ribose         2 × 10.sup.-9                             Arg-lys        glucose        2.5 × 10.sup.-4                           Arg-lys        ribose         5 × 10.sup.-5                             Gly-lys        ribose         5 × 10.sup.-4                             lys            glucose        5 × 10.sup.-4                             6-aminocaproic acid                                                                          glucose        5 × 10.sup.-4                             ______________________________________                                         1--IC.sub.50 were from competition ELISA based on the concentration of th     original proteins or peptides.                                                2--IC.sub.50 for proteins, peptides or sugars alone > 10.sup.-2 M        

Discussion

Thus, this monoclonal antibody recognizes AGEs on different proteins,peptides and amino acids, which AGEs arise from reaction with differentreducing sugars. The antibody of the present invention specificallyrecognizes several glycated proteins in human and rat blood, indicatingthe presence of AGE structures in physiological fluid and in tissues.

EXAMPLE 3 ABILITY TO RECOGNIZE LDL-AGE IN HUMAN SERA AND PLASMA

In this example, LDL (low-density lipoprotein)-AGE in human sera/plasmasamples pretreated to select for LDL was measured by using a combinationof antibodies directed towards AGEs and LDL. The addition ofpolyethylene glycol (PEG) to samples selectively precipitates LDL andthereby improved detection of LDL-AGE. This assay provides fordetermining levels of AGE formation on LDL without detection of otherAGE complexes that might be present in the blood. To determine levels ofAGE on LDL complexes, LDL from human sera or plasma samples wasselectively precipitated using 6-10% PEG and redissolved in buffercontaining 1% SDS detergent. The samples were diluted in Assay Bufferand used in the sandwich protocol described in Materials and Methodsbelow. The assay detects the presence of AGEs on LDL by capturingAGE-modified molecules through binding to immobilized monoclonalantibody 4G9, and then detects captured LDL-AGE complexes by using ananti-ApoB antibody.

Materials and Methods

Levels of LDL-AGE were measured using an ELISA sandwich assay. Onehundred μl of serum or plasma were diluted in PBS containing PEG (6%final concentration) in a final volume of 1 ml and allowed to stand for10 minutes. To obtain LDL, samples were centrifuged at 14000 r.p.m. for5 minutes and the supernatant was discarded. The LDL pellet wasdissolved in 50 μl of PBS containing 1% SDS and allowed to standovernight at room temperature. Next, 950 μl of Assay Buffer comprising1% BSA, 50 ml of 1M borate solution, 0.01% EDTA in 950 ml PBS, pH 8.0,was added.

The LDL-AGE assay was performed using 50 μl of sample per well. Thewells were pre-coated with mAb 4G9 by adding 100 μl per well of mAb 4G9diluted 1:10 in PBS and incubated overnight at 4° C. Antibody coatingsolutions were removed and the plate was washed 6 times with TBS-T WashSolution. The plate was then blocked with Assay Buffer in PBS, 200 μlper well, and incubated for one hour at 37° C. Assay Buffer was thenremoved and the plate washed 6 times with TBS-T Wash Solution. Fifty μlof Assay Buffer was added to each well prior to addition of sample.Eighty μl of a 5 mg/ml stock solution of naturally occurringAGE-modified LDL purified from human blood (Cappel Company, #59392) wasdissolved in 100 μl of a PBS solution containing 1% SDS and allowed tostand for 30 minutes. This solution was then diluted with 1.82 ml ofAssay Buffer to give a 200 μg/ml standard stock solution. The stocksolution was then serially diluted 2-fold to obtain standard solutionsin the range of 50-3.12 μg/ml.

The samples and standards were incubated on the plate for 1 hour at 37°C. and then washed 6 times as before. AGE-specific LDL binding wasdetected using horseradish peroxidase conjugated-antibody against ApoBprotein (Biodesign International, Kennebunk, Me.) diluted 1:500 in AssayBuffer and incubated for 1 hour at 37° C. The addition of the OPDsubstrate (Sigma Chemical, St. Louis, Mo.) allowed visualization ofdetected complexes at 450 nm.

Results

The results are presented in FIG. 1 which shows the normal human LDL-AGEdilution curve as detected with 4G9 monoclonal antibody.

EXAMPLE 4 ABILITY TO RECOGNIZE IgG-AGE IN HUMAN SERA AND PLASMA

Detection of AGE-modified molecules in blood provides evidence for theonset or progress of diseases associated with this phenomenon. Thisexample demonstrates detection of IgG-AGE in human sera/plasma withmonoclonal antibody 4G9.

To determine levels of IgG-AGE, dilutions of serum samples were made inAssay Buffer and applied to the 4G9-coated wells. Horseradish peroxidase(HRP)-conjugated goat anti-human IgG then acts as a detector antibody.Color development produced by the enzymatic conversion of OPD, asubstrate for HRP, is measured to indicate the amount of AGE present.FIG. 2 shows the results of his procedure.

Materials and Methods

Levels of AGE were measured using an ELISA sandwich assay described asfollows. The wells were coated with mAb 4G9 by adding 100 μl per well ofmAb 4G9 in protein-free media diluted 1:10 in PBS and incubatedovernight at 4° C. Antibodies were removed and the plate was washed 6xwith TBS-T Wash Solution containing 0.05% Tween 20. The plate was thenblocked with Assay Buffer (1% BSA, 50 mM borate, 0.01% EDTA in PBS), 200μl per well, and incubated for one hour at 37° C. The Assay Buffer wasthen removed and the plate washed as before. Fifty μl of Assay Bufferwas added to each well prior to addition of sample. Naturally occurringAGE modified human IgG (Sigma Chemical, St Louis, Mo.) was diluted inAssay Buffer to give a range of concentrations from 25 ng/ml to 5.25μg/ml and used as a standard. The IgG-AGE assay was performed using 50μl of sample per well.

The IgG-AGE solutions were incubated on the plate for 1 hour at 37° C.and then washed. Bound AGE was detected using horseradish peroxidaseconjugated goat anti-human IgG (Sigma Chemical, St. Louis, Mo.) diluted1:500 in Assay Buffer and incubated for 1 hour at 37° C. The addition ofthe OPD substrate (Sigma Chemical, St. Louis, Mo.) allowed visualizationof detected complexes at 450 nm.

Results

FIG. 2 shows the normal human serum IgG dilution curve. This data, aswell as the LDL-AGE results of Example 3, show that 4G9 detects AGEmodifications formed on proteins in vivo.

EXAMPLE 5 DETECTION OF SERUM-AGE PEPTIDE LEVELS

The use of the monoclonal antibody of the present invention as anindicator of conditions where increased levels of AGEs are likely to bedetected was explored with respect to the analysis of serum-AGE peptidelevels. More particularly, the ability to detect increased levels ofserum-AGE peptides was investigated utilizing the present monoclonalantibody. Thus, serum from 10 normal and 10 diabetic subjects wasdiluted 1:3 in PBS and was subjected to fractionation through an AmiconMicrocon 10 microconcentrator according to the manufacturer'sinstructions. Thus, 50 μl of the ultrafiltrate containing low molecularweight molecules, including for instance, peptides of less than 10,000molecular weight, was added to microtiter wells that had been coatedwith BSA-AGE in a competitive ELISA assay procedure as described inMakita et al. (1992), J. Biol. Chem. 267(8):5133-5138. This procedurewas varied, however, in the following fashion:

1. The wash solution was TBS-T Wash Solution as described earlierherein;

2. The primary antibody used was the 4G9 monoclonal antibody of thepresent invention;

3. The secondary antibody used was a goat anti-mouse IgG conjugated toalkaline phosphatase (Cappel) and incubated at 37° C. for 45 minutes.Thereafter, the wells were washed 6 times with TBS-T Wash Solution and100 μl of PNPP substrate (Sigma #N2507, St. Louis, Mo.) diluted indiethanolamine buffer made according to the substrate manufacturer'spackage insert was added and incubated for 30 minutes. The OD of thereaction product was measured at 410 nm in a Dynatech MR5000 microtiterplate reader.

The values were expressed per milliliter of serum, and are shown in FIG.3.

EXAMPLE 6 DETECTION AND MEASUREMENT OF URINARY AGE LEVELS IN RATS

Urinary AGE levels were examined in rats, likewise utilizing as part ofthe diagnostic kit and protocol, the monoclonal antibody of the presentinvention. Thus, urine collected from rats housed in metabolic cages wascentrifuged at 14,000 rpm for 10 minutes to remove debris, diluted 1:30in PBS and subsequently passed through an Amicon Microcon 10microconcentrator using the procedure according to the manufacturer'sinstructions. Fifty μl of the ultrafiltrate that contains, among othersmall molecules, peptides of less than 10,000 MW, was added tomicrotiter wells that had been coated with BSA-AGE in the competitiveELISA assay procedure described in Makita et al., and modified asdescribed in Example 5, above. After substrate incubation forapproximately 1 hour, the wells were read in a microtiter plate readerat 410 nm. The values were expressed as AGE U/ml (defined in WO 93/13421by Bucala) of urine per daily volume of urine collected in ml, and theresults are set forth in FIG. 4.

EXAMPLE 7 DETECTION AND MEASUREMENT OF AGE LEVELS IN RAT SKIN

In this example, an assay of levels in rat skin was conducted.Accordingly, a two square-inch of rat skin was trimmed to removeconnective tissue and muscle. The epidermis and dermis of the skinsample were separated from each other, and the dermis was then mincedinto small pieces. The tissue was dried overnight in a Speed Vac (SpeedVac Plus, SC210A, Savant Instruments), and the following day the driedtissue was disaggregated using a spatula. The resulting tissue was thendelipidated using 5 ml of 1:1 chloroform/methanol (3 times). Thesupernatants were discarded, and the tissue pellet then dried for aperiod of 2 hours in a Speed Vac. A 1 mg/ml solution of collagenase inPBS (Collagenase-B - Boehringer-Mannheim) was then prepared. A digestionreaction prepared at a concentration of 60 mg of dried tissue per 1 mgof collagenase, with 20 μl of toluene per ml to prevent contamination.

The sample thus prepared was then agitated at 37° C. for 48 hours in aglass tube, after which it was centrifuged at 12,000 rpm at 4° C. for 20minutes in a plastic tube. The supernatant was then transferred to anEppendorf tube and heated at 70° C. for 1 hour, after which it was againcentrifuged at 12,000 rpm at room temperature, and the supernatant wascollected. The sample was then subjected to pepsin digestion using 200micrograms of pepsin in 0.01N HCl per 1 ml of sample. The pH of thesample was adjusted to 2.0 using 12N HCl. The sample was thereafterincubated in a water bath at 37° C. for 30 minutes. 6 N NaOH wasutilized to adjust the sample pH to 7.0.

The sample was then fractionated using an Amicon Microcon 10microconcentrator and the ultrafiltrate was then analyzed in acompetitive assay (Makita et al.) in accordance with the presentinvention for AGE content. The hydroxyproline (collagen) content wasanalyzed according to the procedure of Stegmann, H. and Stalder, K.,Clin. Chim. Acta 18:267-271 (1967). The sample values are expressed inAGE U/mg (defined in WO 93/13421 by Bucala) collagen and are set forthin FIG. 5.

This invention may be embodied in other forms or carried out in otherways without departing from the spirit or essential characteristicsthereof. The present disclosure is therefore to be considered as in allrespects illustrative and not restrictive, the scope of the inventionbeing indicated by the appended Claims, and all changes which comewithin the meaning and range of equivalency are intended to be embracedtherein.

What is claimed is:
 1. A method for detecting the presence of advancedglycosylation endproducts (AGES) in a biological sample comprising thesteps of:a) contacting a sample suspected of containing AGEs with amonoclonal antibody or antigen binding fragment thereof under conditionswhich allow for the formation of reaction complexes comprising themonoclonal antibody or antigen binding fragment thereof and the AGEs;and b) detecting the formation of reaction complexes comprising themonoclonal antibody or antigen binding fragment thereof and AGEs in thesample; wherein detection of the formation of reaction complexesindicates the presence of AGEs in the sample, and wherein the monoclonalantibody or antigen-binding fragment thereof is monoclonal antibody 4G9as produced by hybridoma 4G9, deposited with the American Type CultureCollection (ATCC) and assigned Accession Number CRL
 11626. 2. The methodof claim 1 wherein the monoclonal antibody or antigen binding fragmentthereof is bound to a solid phase support.
 3. The method of claim 2which further comprises contacting the sample with a labelled advancedglycosylation endproduct (AGE) in step (a), and removing unboundsubstances prior to step (b), and wherein the formation of reactioncomplexes in the sample is detected by observing a decrease in theamount of labelled AGE in the sample.
 4. The method of claim 2, whereinthe formation of reaction complexes is observed by detecting the bindingof a labelled anti-AGE antibody to the complex of the monoclonalantibody or antigen binding fragment thereof and the AGE.
 5. The methodof claim 4, wherein the labeled antibody demonstrates an immunologicalcharacteristic selected from the group consisting of cross-reactivitywith serum-AGE proteins, serum-AGE lipids, serum-AGE peptides, LDL-AGE,Hb-AGE, and collagen-AGE.
 6. The method of claim 1 wherein themonoclonal antibody or antigen binding fragment thereof is labelled. 7.The method of claim 1 wherein an AGE is bound to a solid phase support.8. The method of claim 7, which further comprises contacting the samplewith an AGE in step (a), and removing unbound substances prior to step(b), and wherein the monoclonal antibody or antigen binding fragmentthereof is labelled and the formation of reaction complexes in thesample is detected by observing a decrease in the amount of label. 9.The method according to claim 1, wherein the AGE is an low densitylipoprotein (LDL)-AGE.
 10. A method for evaluating the level of AGEs ina biological sample comprising:(a) detecting the formation of reactioncomplexes in a biological sample according to the method of claim 1; and(b) evaluating the amount of reaction complexes formed, which amount ofreaction complexes corresponds to the level of AGEs in the biologicalsample.
 11. A method for detecting or diagnosing the presence of adisease associated with elevated AGE levels in a mammalian subjectcomprising:(a) evaluating the level of AGEs in a biological sample froma mammalian subject according to claim 10; and (b) comparing the leveldetected in step (a) to a level of AGEs normally present in themammalian subject; wherein an increase in the level of AGEs as comparedto normal levels indicates a disease associated with elevated levels ofAGEs.
 12. A method for monitoring the course of a disease associatedwith elevated AGE levels in a mammalian subject comprising evaluatingthe level of AGEs in a series of biological samples obtained atdifferent time points from a mammalian subject according to the methodof claim 10, wherein an increase in the level of AGEs over timeindicates progression of the disease, and wherein a decrease in thelevel of AGEs over time indicates regression of the disease.
 13. Amethod for monitoring a therapeutic treatment of a disease associatedwith elevated AGE levels in a mammalian subject comprising evaluatingthe levels of AGEs in a series of biological samples obtained atdifferent time points from a mammalian subject undergoing a therapeutictreatment for a disease associated with elevated AGE levels according tothe method of claim 10, wherein a decrease in the level of AGEs overtime indicates an effective therapeutic outcome.
 14. A method fordetecting the onset and/or monitoring the course of diabetes comprisingperforming the method of any one of claims 11 to
 13. 15. A test kit formeasuring the presence or amount of AGEs in an analyte, comprising:a) amonoclonal antibody or an antigen binding fragment thereof, whichmonoclonal antibody or antigen binding fragment is monoclonal antibody4G9 as produced by hybridoma 4G9, deposited with the American TypeCulture Collection (ATCC) and assigned Accession Number CRL 11626; b)labeled AGE or a labeled secondary antibody which binds 4G9 (ATCC CRL11626); and c) directions for use of the kit.
 16. The test kit of claim15, wherein the monoclonal antibody or antigen-binding fragment thereofwhich is characterized by an activity selected from the group consistingof reactivity with serum-AGE proteins, serum-AGE lipids, serum-AGEpeptides, LDL-AGE and collagen-AGE.
 17. The test kit of claim 15 whereinthe anti-AGE antibody is irreversibly associated with a solid phase. 18.The test kit of claim 15 which further comprises a labelled anti-AGEantibody, which labelled anti-AGE antibody is reactive with invivo-produced AGEs.
 19. The test kit of claim 15 which further comprisesa labelled anti-low density lipoprotein antibody.
 20. The test kit ofclaim 15, wherein the low density lipoprotein is ApoB.
 21. The test kitof claim 15 which further comprises a labelled AGE.
 22. The test kit ofclaim 15 which further comprises an AGE.
 23. The test kit of claim 22,wherein the AGE is bound to a solid phase and the antibody is labelled.